Filtration process for glass furnace dust

Abstract

A method for filtering the dust in gaseous emissions discharged from a glass furnace includes filtering the emissions at a traverse speed of at least 0.1 m/sec with at least one filtering element downstream of the furnace, and regenerating the filtering element by washing using a water-based solvent which is capable of dissolving and/or washing away most of the filtered dust.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. A method for filtering dust from gaseous emissions coming from a glass furnace, comprising the steps of: filtering at least a portion of dust contained in at least a portion of emissions from a glass furnace at a traverse speed of at least 0.1 m/sec using a filtering element installed downstream of the furnace;   regenerating the filtering element by washing using at least one water-based solvent, capable of dissolving and washing away at least a portion of the dust filtered.   
     
     
       2. A method according to claim 1, wherein in the emissions are filtered at a temperature between 150° C. and 500° C. 
     
     
       3. A method according to claim 1, wherein the filtering element is positioned within at least one of a pipe conducting the emissions from the furnace, a pipe conducting emissions from regenerator flues and a smokestack, wherein the filtering element has a traverse surface for gas/smoke roughly at least as large as the surface area of the cross section of said at least one of a pipe and a smokestack. 
     
     
       4. A method according to claim 1, wherein said filtering element has a maximum initial load loss of 10,000 Pa. 
     
     
       5. A method according to claim 1 wherein said filtering element that has an absolute filtration threshold of at least 20 μm. 
     
     
       6. A method according to claim 1, wherein the filtering element has a base of metal or ceramic, constructed of sintered particles, sintered fibers, textile fibers or felt fibers. 
     
     
       7. A method according to claim 1, further comprising the step of offsetting at least a portion a load loss created by the filtering element using at least one device installed downstream of the filtering element. 
     
     
       8. A method according to claim 7 wherein said step of offsetting further comprises adjusting an upstream flap mechanism to offset, at least in part, the variations in load loss over time induced by the filtering element. 
     
     
       9. A method according to claim 1 wherein the step of regenerating further comprises regenerating the filtering element periodically according to at least one of a frequency coinciding with that of the furnace inversion cycles and a set increase threshold value for the load loss created by the filtering element. 
     
     
       10. A method according to claim 1 further comprising the step of regenerating the filtering element by washing with a sodium carbonate NaOH-based solvent, after the step of regenerating the filter element by washing with a water-based solvent has been repeated a predetermined number of times. 
     
     
       11. A method according to claim 1 further comprising the step of maintaining the load loss created by the filtering element by using a revolving strip. 
     
     
       12. A method according to claim 1 further comprising the step of removing a used filtering element from the furnace in order to regenerate the used filter and replacing the used filtering element with at least one of a new and a regenerated filtering element. 
     
     
       13. A method according to claim 1 wherein said step of regenerating further comprises regenerating the filtering element while it is installed in the furnace without removing it from its filtration position, by providing for the use of at least two filtering elements. 
     
     
       14. A method according to claim 1 wherein the step of regenerating further comprises at least one of soaking in a solvent bath, stationary or mobile spraying, and irrigation. 
     
     
       15. A method according to claim 1, further comprising the step of recycling at least part of dust-laden solvent generated during said step of regenerating the filtering element by wetting the vitrifiable materials with the dust-laden solvent prior to loading them into the furnace. 
     
     
       16. A method according to claim 1, wherein said step of filtering further comprises adjusting an amount of filtration so that no more than 150 mg of dust per Nm 3  of smoke standardized to 8% O 2 , no more than 50 mg/Nm 3  at 8% O 2  and no more than 0.35 kg of dust per ton of melted glass is discharged from the furnace. 
     
     
       17. A glass furnace filtering device comprising: a first filtering element provided at an exhaust pipe through which gaseous emissions from a glass furnace are guided, said first filtering element provided downstream of the furnace, said first filtering element configured to filter dust in the gaseous emissions at greater than 0.1 m/sec.   
     
     
       18. A glass furnace filtering device according to claim 17, wherein said first filtering element has a load loss of no more than 10,000 Pa, an absolute filtration threshold of at least 20 μm and an effectiveness level of at least 30%. 
     
     
       19. A glass furnace filtering device according to claim 17, further comprising: a moveable filter holder device configured to position said first filtering element, during filtration, substantially across the section of a pipe or of a smokestack of a glass furnace through which the gaseous emissions are fed, said moveable holder also configured to periodically extract said first filtering element in order to regenerate or replace it.   
     
     
       20. A glass furnace filtering device according to claim 17, further comprising: a second filtering element mounted in parallel with said first filtering element in said exhaust pipe;   wherein said furnace filter is configured to operate said first and second filtering elements in alternating fashion.   
     
     
       21. A glass furnace filtering device according to claim 17, further comprising: at least one offsetting mechanism for offsetting a load loss in the exhaust pipe, downstream from said furnace, generated by said first filtering element, said offsetting mechanism including a fan.   
     
     
       22. A glass furnace filtering device according to claim 17, further comprising: a regeneration mechanism configured to wash said filtering element with water, said regeneration mechanism comprising at least of baths, mobile or stationary spray distributors, and irrigation mechanisms; and   a wash water collection mechanism configured to collect the water used by said regeneration mechanism and to reintroduce the water into a wetting area for wetting vitrifiable materials prior to placing them in the furnace.   
     
     
       23. A glass furnace filtering device according to claim 22, wherein said regeneration mechanism further comprises means for washing with sodium carbonate. 
     
     
       24. A glass furnace filtering device according to claim 22, wherein said wash water collection mechanism comprises: at least one retention tank equipped with at least one composition homogenizing mechanisms; and   at least one homogenization and temperature control mechanism.   
     
     
       25. A method according to claim 1 wherein the traverse speed is between 1 to 10 m/sec. 
     
     
       26. A method according to claim 1, wherein said filtering element has a maximum initial load loss of 4,000 Pa. 
     
     
       27. A method according to claim 1, wherein said filtering element has a maximum initial load loss between 100 and 1000 Pa. 
     
     
       28. A method according to claim 1 wherein said filtering element that has an absolute filtration threshold between 40 and 80 μm. 
     
     
       29. A method according to claim 7, wherein the offsetting device is a fan. 
     
     
       30. A method according to claim 29 wherein the fan includes at least one of an adjustable rotation speed and an adjustable angle of inclination of the blades. 
     
     
       31. A method according to claim 14 wherein the step of regenerating further comprises drying with compressed air. 
     
     
       32. A glass furnace filter according to claim 18, wherein said filtering element has an effectiveness level between 50 and 95%. 
     
     
       33. A glass furnace filtering device according to claim 21, further comprising: an upstream pressure sensor provided on an upstream side of said first filtering element;   a downstream pressure sensor provided on a downstream side of said first filtering element;   at least one variable offset mechanism for offsetting the variation in load loss over time due to the filtering element, said variable offset mechanism including a flap controlled according to a pressure drop across said as detected by said upstream and downstream pressure sensors.   
     
     
       34. A glass furnace filter according to claim 24, wherein said wash water mechanism further comprises at least one of pH controlling mechanism configured to control the pH of the water and means for filtering solid particles at the outlet of said retention tank. 
     
     
       35. A method according to claim 1, wherein the traverse speed is within the range of at least 1 to 10 m/sec.